If I remember correctly, they say that the rocks in the cavern are merely "the most delicious". So this is really the equivalent of a kid opening the fridge and seeing that they're out of pizza rolls and whining that there's nothing to eat.
Do different rocks have different tastes? Do they season one sort of rock with others? What is the cooking equivalent for a rock? Maybe grinding it up and recombining to different sorts of tasty concrete?
Considering that there's a side quest in to where a rock connoisseur is looking for a rare type of flint, I'd say theres definitely different flavors of rock. And in terms of cooking, the gorons have grills where they literally just cook rocks. I'm not sure if they're trying to metamorphize them into different rocks or what's actually going on, but they don't eat their rocks raw. I wonder if concrete would be like a soup for them?